1. Field of the Invention
This invention concerns gastric-disintegrable aspirin that are coated with a thin film of plasticized ethylcellulose.
2. Description of the Prior Art
Coatings for analgesic tablets, such as aspirin, acetominophen and ibuprofen, can serve as any of several functions, e.g., sustained release, enterosoluble, taste-masking, with the coating formulation being tailored to achieve the desired performance objectives.
U.S. Pat. No. 4,302,440 issued to John et al describes easily-swallowed, gastric-disintegrable aspirin tablets thinly coated with plasticized hydroxypropylmethyl cellulose that is applied via an aqueous spray-coating method.
Enterosoluble aspirin tablets are prepared in U.S. Pat. No. 4,107,647 issued to Ohno et al by coating tablets, via an aqueous system, with hydroxypropyl methylcellulose phthalate that is acid treated after coating. Such tablets pass intact through the stomach but become disintegrated in the intestinal tract.
The cellulosic materials typically used in these coating applications are well known as coating agents. Hydroxypropyl methylcellulose is a water-soluble cellulosic that is commonly used for rapidly-soluble coatings, which are readily disintegrable in the stomach. Enterosoluble cellulosics that are popular include cellulose acetate phthalate and hydroxypropyl methylcellulose phthalate.
Ethylcellulose is a water-insoluble polymer that is known to be useful in sustained release applications. U.S. Pat. No. 4,508,702 describes the encapsulation of aspirin crystals or particles with ethylcellulose having a minor component of water-soluble hydroxypropylcellulose. Sustained release aspirin granules are also described in U.S. Pat. No. 3,341,416 issued to Anderson et al and No. 3,155,590 issued to Miller et al, both of which employ ethyl-cellulose as the primary component for forming a rigid seamless protective coat around each aspirin particle.
The present coating invention employs water-insoluble ethylcellulose, conventionally used in sustained release applications, in a manner which provides a rapidly-disintegrable, taste-masking coating for analgesic tablets, that are nevertheless rapidly solubilized or disintegrated.